The other reason of black screen is that some motherboards set wrong PCI Bus Latency Timer value in BIOS. In tab "Hardware" in Behold TV program settings you may change this value in Device configuration and so force to work PCI SAA713x videodecoder. The recommended PCI Latency value is 16-64.

Also in server versions of Windows OS partially or fully turned off video acceleration by default in order to increase reliability. This also results in "black screen" or color distortion while working in different video output methods. Open display properties, swith to Settings, press "Troubleshooting" and set hardware acceleration to maximum. Run dxdiag.exe utility ("Start" –> Run… –> dxdiag.exe) and check that the hardware acceleration of DirectDraw and Direct3D is fully turned on in "Display" settings of the utility.